Compressor-regulating apparatus



Feb. 2l, 1928.

L. F. HOFFMAN COMPRESSOR REGULATING APPARATUS Neuf l...

Lean E Hoffman Y/A WOR/VW n Filed Au.

Patented Feb. 21,1928.

UNITED STATES PATENT OFFICE.

LEON F. HOFFMAN,` OF FRANKLIN, PENNsYLvANrA, AssiGNoB. 'ro CHIOAGOFNEU- MATIO TOOL COMPANY, OF NEW YORK, N. Y., A COEFOEATION OF' NEW JERSEY.

COMPRESSOR-REGULATING APPARATUS.

Aqaplirration` llled August 3, 1925. Serial No. 47,829.

This invention relates to apparatus for automatically controlling the operation of compressors, pumpsgand the like. -It is particularly adapted andV intended for use with compressors Operated by prime movers having a low starting torque such as the squlrrel cage type of electric motor. p

With automatic start and stop control apparatus for prime movers of the type delo scribed it is essential that the .motor be allowed tol attain full speed before the compressor loads up. Otherwise serious disturbances and possible damage to the prime mover are liable to occur.

Among the objectsof the invention are t provide simple and positively operating apparatus which will delay the loading of thel compressor until the prime mover has at-` tained full speed, which is applicable to 2o centrifugal control apparatus already in use, which is adjustable, Which is inexpensive to manufacture and install, and in general to improve prior devices in the interests of kmore elhcient and satisfactory service. y

In order to illustrate theinvention `one concrete'embodiment thereof is shown in the accompanying drawing in which:

Fig. `1 is a side elevational view of acompressor equipped with automatic control- 3o ling apparatus; y y y y Fig. `2 is a vertical sectional view of the controlling apparatus shown in Fignrl and indicating the connection'to the valves controlled thereby,A the latter being also shown in vertical section; and

Fi 3 is a vertical sectional View similar a prime mover having a low starting torque,` such as a squirrel cage electric motor (not shown, through a suitable driving connec-` tion such asa belt C engaging a ily-wheel D mounted on the crank shaft E of the compressor. Thesupply and exhaust `of the compressed fluid to and from the unloadas ing valves a andwater controlvalve b iscontrolled by a speed responsive device indicated at 4,. shown in elevation in Fi 1; and insection in Figs. 2 and 3. This evice is arranged to be driven at a speed proportionate to the speed of the compressor b a suitable connection such as a belt 5 engaging apulley on shaft E ofthe compressor and a pulley 6 on device 4.

Referring now to Figs. 2 and` Sthe control device 4 has a casing 7 providedwith chambers 8 and 9 separated by a partition 10, a bore l0a serving to connect saidchambers. A member 11 having a central bore is `disposed in chamber 9 and extends into bore 10, said member having a series of radial ports 11a connecting: the bore of member 11 `Withchamber 9. Radial ports 11b adjacent to the top of member 11 are arrangedto connect. the bore of the latter with atmosphere. As indicated member 1l has threaded engagement with a cap `plate l2 for casing 7, which plate sup rts the standard 13 in `which is mounted)O for y reciprocatory movement a member la carla` acted upon by a suitable centrifugal organization X of conventional" form driven by pulley 6.1` When the compressor` is not running at# all or running slowly the arts are in the position shown in Fig. 2 Wit i the valve piston 14' so dis Osed as to establish connection between c embers V8 and 9. Chamber 8 is connectedto receiver pressure by pipe 8a" and chamber 9 communicates with valves a and b by pipe 9*; Thus receiver pressure passes to valves a and b and holds i them inoperative as shown in Fig. 2. When the compressorspeeds up the centrifu al organization X forces the reciprocatory eement 14 downwardly so that the "valve piston `14" is disposed belowports 11` (Fig. 3) thereby closingconncctionbetween chambers `8 and Qiand connecting chamber 9 to atmos` phere through ports 11l lthe bore of port 11 and" port 1l". vSuitable means which may include springs thereupon 'act upon valves a and-b to move the `same to operative condition.`

" In order thatthere may not betoo lrapid a movement o thevalve iston 14' which would load the com ressor efore thefprime mover had `at-taine 1 full speed; means are provided for retarding the downward movement of the piston. Preferred means for this purpose comprise a suitable dash pot device 15 having threaded engagement with a bore in casing 7 communicating with chamber 8 and in line with bore 10a. This device comprises a cup shaped casing 16 threaded into the aforesaid opening and having its lower open end sealed by a threaded closure member 17 formed with a cylindrical extension 17 a disposed within member 16. A piston 18 has a lapped fit with the interior of cylindrical extension 17a and a rod 18a secured thereto extends through a bore in casing'l, through chamber 8, and into the bore of member 11 to engage piston valve 141. A coiled spring 19 seated in cylinder 17L and engaging the piston 18 maintains rod 18a in yielding engagement with vpiston valve 14". A plug 16l in the side of casing 16 enables the latter to be partly filled with oil. The oil can pass freely into the lower end of the cylinder 17a through interconnecting bores 2O and 21, in closure 17, and a passage 22 provided with a check valve 23. Limited reverse flow of the oil from cylinder 17L to the interior of casing 16 is permitted by a passage 24 controlled by an adjustable plug or needle valve 25.

For the salte of clearness the body of oil in dash pot 15 is not shown.

With the compressor at rest the control apparatus is in its normal condition as shown in Fig. 2,V the high pressure fluid from the receiver is connected to pipe 9il through chamber 8, the bore of member 11 and ports 11a so that the water valve b is held closed by pressure fluid and the unloading valves a are held open to unload the compressor. On starting the motor rod 14Kt carrying piston valve 14b starts to move down and this movement is resisted by spring 19 of the dash pot and by the oil trapped in the lower end of cylinder-'17L beneath piston 18 so that the l-atter moves down slowly as the oil is forced out through the restricted passage 24. By the time that piston valve 14b has passed below and uncovered ports 11 (Fig. 3) the motor has atta-ined full speed and is able to operate the loaded compressor without stalling or damage, the pressure fluid in pipe 9 having been vented to atmosphere through ports 11a, the bore of member 11, and ports 11b. When the compressor is stopped piston valve 14b operated by the centrifugal organization moves upwardy to again establish communication between valves a and b and receiver pressure. Rod 18aL of the dash pot maintains contact with the valve piston by reason of spring 19 and the free access of oil to the `c linder 178L through the check valve 23. ny leakage of pressure fluid along rod 18" into casing 16 of the dash pot device will not affect operation of the latter since the pressure equalizes on the opposite ends of the piston 18 due to the free passing of the oil in casing 1G into the lower end, of cylinder 17et pastcheck valve 23. y

While but one form of the invention has been herein shown and described it is to be understood that the invention is not restricted to the specific details thereof but covers all changes, modifications and adaptations within the scope of the appended claims.

I claim as my invention: l

1. Regulating apparatus for compressors, pumps and the like comprising in combination valves arranged to be rendered inoperative by fluid pressure, a speed responsive de-l vice driven bythe compressor and having a reciproating membercontrolling the admission and exhaust of pressure ,fluid to and from said valves, a rod maintained in contact with said member, and both fluid means and spring means arranged yieldingly to resist movement of saidvrod in one direction so as to retard the exhaust of pressure fiuid from said valve. l

2.1n apparatus of the class described, in combination, a casing having chambers connecting with the fluid pressure supply and with the compressor unloading valves respectively, a control member movable automatically in response to the speed of the compressor for connecting said second chamber to saidy first chamber or to atmosphere, a dash pot device secured to said casing having a member projecting into said chambers and yieldingly engaging said control member' for resisting its movement in one direction, and a spring arranged to offer additional resistance to themovement of said control member in said direction.

3. In apparatus ofthe class described, in combination, a casing having chambers connecting -with the iiuid pressure supply and with the compressor unloading valves respectively, a control member movable automatically in response to the speed of the compressor for connecting said second chamber to said first chamber or to atmosphere, a dash pot device secured to said casing having a uid chamber, acylinder therein, a piston reciprocable in said cylinder, ai member projecting from said piston up into the chambers of said casing to engage said control member, and means permitting free flow of fluid into the cylinder beneath said piston but throttling its reverse flow, thereby to delayv movement of said control member to compressor loading position. Y

4. In apparatus of the class described, in combination, a casing having chambers connecting with the fluid pressure supply and with the compressor unloading valves respec-V tively, a control member movable automatically in response to the speed of the compressor for connecting said second chamber to said first chamber or to atmosphere, a dash pot device secured to said casing having a llt) Contact with said member, and means per` mitting free flow of fluid into said cylinder beneath said piston and adjustably restricting its reverse flow thereby to delay the loading of the compressor.

5. A dash pot device constructed and ai ranged to be secured to the automatic control device for valves of a compressor to prevent premature operation of the latter comprising a hollow dash pot casing having an open end, a closure for said open end having a cylindrical extension Within said casing, a piston re- Y ciprocable Within said cylindrical extension and having a stem projecting beyond said casing te engage the control member of said control device, a spring beneath said piston to urge said stem into Contact with said member, and means permitting free flow of fluid in saidcasing beneath said piston and restricting its reverse flow.

6. A dash pot device constructed and arranged to be secured to the automatic control device for the valves of a compressor to prevent premature operation of the latter comprising ahollow dash pot casing having an open end and a perforated projection for attachment to said device, a closure for said open end having a cylindrical extension rojecting within said casing and in space relation to-the Walls thereof, a piston reciprocable Within said cylindrical extension and forming two chambers within said casing, said piston having a stem extending through said perforated projection of said casing to coo erate With'said control device, a spring Wit in said extension yieldingly to maintain said piston Vremote from said closure, means in said closure member controlling the flow `of liquid between said chambers in said cas` ing, said means permitting free `flow of liquid into the chamber within said extension but restricting its How outwardly thereof.

7. Regulating apparatus for compressors, pumps and the like comprising in combination, valves arranged to be rendered inoperative by fluid pressure, a speed responsive device driven by the compressor and having a reciprocating member controlling the admission and exhaust of pressure fluid to and from said valves, a plunger maintainedin cont-act with said member, and both fluid means and spring means arranged yieldingly to resist movement of said plunger in one direction, said spring means being within said iuid means and arranged to assist in th proper functioning of the latter;

'Signed by me at Franklin, Penna., this 22d day of July 1925.

" LEON F. HOFFMAN. 

